Online physics calculators
Calculate force, kinetic energy, potential energy and momentum with the fundamental formulas of mechanics. Pick a tool from the menu on the left or from the cards below; formulas, notes and frequently asked questions are further down.
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Dynamics and energy
Four calculators for the basic quantities of mechanics. Choose the quantity: the tool opens at the top of this page.
Main formulas
The fundamental formulas are summarized below, with symbols and International System units.
| Quantity | Formula | Symbols | SI unit |
|---|---|---|---|
| Force | F = m · a | m mass, a acceleration | N = kg · m/s² |
| Kinetic energy | Ek = ½ · m · v² | m mass, v speed | J = N · m |
| Potential energy | Ep = m · g · h | m mass, g ≈ 9.81 m/s², h height | J |
| Momentum | p = m · v | m mass, v velocity | kg · m/s |
Fundamental formulas of mechanics with International System units.
Practical notes
Kinetic energy depends on the square of the speed: doubling the speed makes Ek four times larger. If a body falls without air resistance, potential energy turns into kinetic energy and the speed reached is v = √(2 · g · h): from 2 m it reaches about 6.26 m/s. Always use consistent units: mass in kg, speed in m/s, height in m.
Frequently asked questions
How do you calculate force?
With Newton’s second law, F = m · a. Example: a mass of 10 kg with an acceleration of 3 m/s² is subject to a force F = 10 · 3 = 30 N.
How do you calculate kinetic energy?
Ek = ½ · m · v². Example: a 1,000 kg car at 20 m/s has Ek = ½ · 1,000 · 400 = 200,000 J, that is 200 kJ.
How do you calculate gravitational potential energy?
Ep = m · g · h. Example: a 5 kg mass at a height of 2 m has Ep = 5 · 9.81 · 2 = 98.1 J.
What is momentum?
It is the product of mass and velocity, p = m · v, and it is conserved in an isolated system. Example: 2 kg at 6 m/s has p = 12 kg · m/s.